Birds and butterflies must be as confounded as we humans about the change of seasons and when spring has arrived for real. Last week, readers reported sightings of individual monarch butterflies fluttering through backyards in search of nectar and nurseries — host plants on which to lay their eggs.

I saw a hummingbird in my backyard, dipping its long beak into a spurting fountain. I rushed to scour and fill a feeder with bottled nectar, because there are no flowers blooming in my garden — or any area garden, that I know of — to sustain a hummer.

I guess once monarchs and hummingbirds leave their winter homes to migrate north, bad weather does not turn them back. They are programmed genetically to persist.

Garden lovers are nature lovers. Even if you do not consider yourself a gardener, these creatures, tricked like us by Mother Nature into believing spring is here, need immediate human intervention. Clean and fill hummingbird feeders with man-made nectar. Buy milkweed plants, which perform the dual duties of being nectar and caterpillar host plants, to support any monarchs that waft through your yard.

Milkweeds (Asclepias spp.) are the only plants a monarch female will lay eggs on. That’s because her caterpillars only eat milkweed leaves. In addition, she is able to assess the food supply and how many caterpillars it will sustain. She lays one speck of an egg on the underside of a leaf. If another monarch’s eggs or caterpillars already are present on a plant, or the plant is too young to sustain more than one caterpillar, she moves on in search of more milkweed.

The flowers are a preferred nectar source, but monarchs also will feed on flowers with a daisylike structure, including pentas, zinnias, scabiosa, lantana and eupatoriums. The broad, flat blooms make easy landing pads.

Without milkweed plants, the monarch population will continue to decline in the Americas. Native milkweeds are slow to sprout new growth each spring, so scientists urge citizens to plant nursery-grown milkweeds in beds and containers as soon as they appear in stores.

The easiest milkweed to find in North Texas garden centers is Mexican milkweed (A. curassavica), with varieties that bloom red and orange or gold. It is usually an annual in North Texas. Depending on our winter, it may resprout from the root some springs. But after this year’s severe lows, most butterfly gardeners will have to replace their stock.

Assessing reports from local garden centers, there already has been a run on established plants in 1- and 2-gallon pots. It does not matter if the milkweed is blooming when you buy it. Substitute any blooming annual or perennial that attracts butterflies to its nectar. Milkweed leaves to host caterpillars, on the other hand, are especially critical in gardens because more and more farmers are planting crops genetically altered to be resistant to weed-killing herbicides.

In Texas and the Midwest, where native milkweed territories coincided with migrating monarchs, the butterfly-sustaining plants have been eradicated from farmland as weeds.

Local plant sales supported by botanic museums, master gardener programs and native plant associations often have hard-to-find native milkweeds for sale as young plants grown from seed. Texas Discovery Garden’s upcoming butterfly plant sale, open to the public April 25-26, lists eight milkweeds that will be for sale. For details, go to texasdiscoverygardens.org.

When buying milkweed transplants, there is one caveat: Ask if they have been treated with a systemic pesticide. If so, caterpillars may be poisoned by residues. In time, the plants will be safe for caterpillars, but not this spring.

“Our milkweed is not treated with any systemic pesticides and is caterpillar-safe when it leaves our facility,” Jonathan Soukup of Southwest Perennials, a wholesale greenhouse, writes in an email. “Some of these pesticides can remain active over a long period of time and decimate caterpillar populations.

“The downside to not treating [with pesticides] is that plants are more susceptible to damage from other insects, but this is the tradeoff of having a host plant,” Soukup says.

Frisco’s Shades of Green nursery has milkweeds from Southwest and a second supplier.

“We’re monitoring the [second supplier’s] 1-gallon plants to see if aphids show up on them,” writes an employee in an email, “a classic indicator of safety.”

Where to buy

Almost every local garden retailer, including the big-box chains, will stock milkweed this spring. Some nurseries are awaiting their first delivery of Mexican milkweed. Others are sold out and expect more inventory. A few, below, report transplants in various pot sizes, from 4 inches to 2 gallons. The bigger the plant, the sooner they will produce flowers. Call before driving.

To post a comment, log into your chosen social network and then add your comment below. Your comments are subject to our Terms of Service and the privacy policy and terms of service of your social network. If you do not want to comment with a social network, please consider writing a letter to the editor.

About Mariana Greene

Mariana Greene is the Garden Editor and the Home Editor at the Dallas Morning News. She writes the column Gardening Fool and reports on Dallas home design and the North Texas gardening community, with special interests in cottage gardening, provincial antiques, the Arts & Crafts era in the United States and England and urban henkeeping.